Construction method



United States Patent 3,306,000 CONSTRUCTION METHOD Marion D. Barnes, Washington, D.C., assignor, by mesne assignments, to Research Corporation, New York, N.Y., a non-profit corporation of New York No Drawing. Filed Jan. 2, 1963, Ser. No. 248,902 6 Claims. (Cl. 52--747) The present invent-ion relates to the preparation of walls or other structures such as roofs from masonry blocks or other building units.

There is a real need today, particularly in poor and under-developed countries, for simplified, low-cost building techniques and methods which can be efifectively employed using relatively inexpensive equipment and a minimum of skilled labor.

Accordingly, the principal object of the present invention is to provide a new method for building walls, roofs or like structures which effectively satisfy this need. More particularly, it is an object of the invention to provide a method for erecting walls or equivalent structures which can be carried out at low cost and without the use of skilled labor or expensive equipment. Another object of the invention is the provision of a faster and more economical method of assembling masonry blocks or other building units. A further object is to provide means for obtaining walls or like structures which are stronger and otherwise superior to corresponding structures prepared in conventional fashion while at the same time minimizing costs and other prior problems. Other objecst will also be hereinafter apparent.

Broadly stated, the foregoing objects are realized by means of a method which involves stacking the masonry blocks or other building units in place to form the wall, roof or other desired structure without using mortar, cement or equivalent bonding medium between the contactin-g surfaces and then painting or otherwise applying to one or both external faces of the resulting structure, particularly at the joints where the blocks or units come together, a fibrous plastic mix as described herein. The invent-ion is especially advantageous for forming walls or the like from masonry units, e.g. concrete or cement blocks, using a glass fiber-sulphur mix and the ensuing description is primarily directed to this aspect of the invention. However, the use of other compositions and structural units such as wood blocks are also visualized as will be hereinafter apparent.

The success of the invention is due, at least in large measure, to the discovery that the fiber plastic composition used herein, especially the glass fiber-sulphur mix, is remarkably effective in holding together masonry units or the like which have been simply laid together in endto-end relationship without the usual use of mortar or cement between the units. The mix, in molten form, is simply sprayed or otherwise coated onto the exposed surfaces formed by the assembled units. On setting, the mix provides an unexpectedly high bond between the blocks in an unusually short time to give a wall construction which has greater strength than a conventional concrete block wall where mortar is placed between each block.

It will be appreciated that the present process represents a very substantial contribution to the art. The use of mortar or cement between masonry units is obviously time-consuming and necessitates skilled labor for formulating and applying the bonding means. On the other hand, all that is necessary in the present process when working with masonry blocks is to simply stack the blocks in the desired manner followed by painting or otherwise applying the mix to one or both of the external wall surfaces formed by the stacked blocks.

As indicated above, the preferred fiber-plastic mix used herein comprises a mixture of glass fibers and sulphur. Single filaments or fibers may be used but it is preferred to use chopped strand fibers (each strand being made up of many glass fibers or filaments). 'In any event, the fibers which are used should not substantially exceed 0.50 inch in length. Longer fibers tend to ball 'up when dispersed in molten sulphur and do not give uniform compositions. Preferably, the average fiber length is maintained near the maximum of 0.50 inch although lengths as low as .25 inch give satisfactory results. It is desirable to use a mix wherein the fibers are more or less uniform in size and evenly distributed throughout the formulation. This insures the most effective bonding and highest possible tensile strength, with the fibers randomly oriented at the joints of the blocks.

Commercially available sulphur may be used herein and this will normally have a degree of purity in the range of 97 to 99.9+%. Generally speaking, from 50 to 95 parts of sulphur with to parts preferred, will be included per parts by weight of the overall formulation.

The formulation desirably includes an appropriate plasticizer for the sulphur. Among its advantages, the plasticizer improves the impact resistance of the composition. Any conventional sulphur plasticizer, e.-g., an aliphatic or aromatic polysulphide, or mixture of these, may be used for this purpose, provided the plasticizer or plasticize-r mix is stable at the temperatures of formulation and application. However, it is preferred that the plasticizer component be selected from (1) an aryl polysulphide where the bridging links between adjacent sulphur atoms in the polymer chain include an aromatic ring, e.g., monocyclic a-rylene and (2) an aliphatic polysulphide where the bridging links between adjacent sulphur atoms include aliphatic ether groups, e.g. -CH OCH OCH or the like.

As an example of a suitable aromatic polysulphide there may be mentioned styrene polysulphide which is characterized by the repeating unit C H C H S and is available as Thiokol polymer ZM399. Another polysulphide plasticizer in this group is one having the repeating unit CH C H.,CH S where x is an integer, erg. 2. As will be appreciated, these aryl polysulphide plasticizers are characterized by the recurring unit RS where x is an integer, typically in the range of 2 to 16 and R is arylene, preferably vinylarylene or :alkarylene since the presence of vinyl or alkylene groups in combination with the aryl radical give exceptionally good results.

The aliphatic polysulphides containing ether linkages may be exemplified by Thiokol LP3. structurally, this polymer has the recurring unit where x has a value of 4. This polymer is further characterized by a viscosity at 77 F. of approximately 10 poises and a molecular weight of about 1000. Other aliphatic polysulphides which include similar or equivalent ether linkages may also be utilized provided, of course, they are stable at the formulating and applicating temperatures and function to plasticize the sulphur.

The preferred plasticizers of the invention show a number of advantages over other sulphur plasticizers. For example, these plasticizers are essentially odorless whereas polyalkylene polysulphides, such as polyethylene tetrasulphide, have objectionable odors and are generally disagreeable to Work with. It has also been found that the preferred plasticizers of the invention, in contrast to polyethylene tetrasulphide, do not darken the composition on heating and they effectively eliminate or minimize the tendency of the sulphur to increase in viscosity at elevated temperatures above the melting point thereof thus greatly improving the application characteristics of the present formulation.

The total plasticizer content in the compositions used herein will normally fall within the range of 130 parts by weight, per 100 parts of the total formulation, although about 10 parts is usually preferred. Particularly effective results are obtained using a plasticizer mixture comprising equal parts by weight of the two polysulphide polymers LP-3 and ZM-399 and a preferred formulation includes 5 parts LP3 and 5 parts ZM-399, by weight, although other proportions also may be employed depending on the ultimate uses which are visualized. For example, using a plasticizer mixture containing equal parts of the indicated plasticizers LP3 and ZM399, satisfactory results have been obtained using as little as 2 parts of the plasticizer mixture or as much as 20-30 parts thereof. Additionally, while the use of a plasticizer mixture containing equal parts by weight of the two plasti cizers is preferred, it is possible to use unequal ratios of LP-3 and ZM399, e.g. a 40/60 mixture.

In certain cases, it may be possible to use other glass fiber-plastic compositions in place of the glass fiber-sulphur mix described above. Thus, the sulphur may be replaced by an appropriate thermoplastic or even thermosetting resin. Any such resin which is quick setting and demonstrates good adherence to the structural material may be used. Sulphur has good adherence to a wide variety of materials, including wood and the conventional type masonry unit or block and is, therefore, of especial importance. However, alternatives include the thermosetting resins like the epoxy, urea-formaldehyde, phenolformaldehyde, melamine-formaldehyde, polyester and alkyd resins. Thermoplastic materials include the polyolefins, polyvinyl resins, acrylics, polyamides, coumaroneindene, etc.

The invention is suitable for use with any of the conventional type masonry units including those generally referred to as cinder block, concrete block, ceramic block, tile, brick, etc. Other types of structural units may also be used, e.g. wood blocks, or wood fiber panels with or without a cement coating thereon, provided the glassfiber sulphur mix or the like is sufficiently adherent thereto. Thus, for example, wood fiber panels may be placed in edge-to-edge relationship and treated according to the invention for the purposes of preparing a roof.

Combinations of different structural units such as wood and masonry blocks may be joined together in the manner described herein. In general, the more porous the structural unit, the better the resulting bond will be and the bond may be further improved by selecting materials which will react to give a chemical-type bond between the coating material and the structural unit itself.

The coating compositions used herein may include various additives and fillers, e.g., a pigment, to provide special decorative effects.

The bonding medium of the invention may be applied over the entire external surface or surfaces of the wall structure so as to produce a decorative, waterproof and otherwise finished wall. Alternatively, the bonding composition may simply be applied as a stripe of, for example, one inch or more, at the periphery of each block or unit to cover the joint and bond the units together.

The glass fiber/sulphur compositions of the invention may include a small amount of any alkaline material, e.g., an organic amine or alkali metal or alkaline earth metal carbonate, which is stable at the temperatures used. Calcium carbonate is especially desirable for this purpose. This alkaline substance contributes substantially to the serviceability of the coating compositions used herein. In particular, the carbonate or other base appears to serve as a catalyst which accelerates introduction of the plasticizer into the sulphur. Another advantage is that the alkaline substance apparently combines with the sulphur to improve the mechanical properties of the coating composition. The carbonate also functions to neutralize acidity contained in the plasticizer and any acid which may be formed. The amount of carbonate or other alkali may be varied although it will generally fall in the range of .5 to 2 parts per parts of formulation with 1 part preferred.

Any convenient method may be used for applying the coating compositions of the invention, the important thing being to obtain a uniform coating on the surface which is being treated, particularly at the periphery of the blocks or other assembled units. Thus, the coating may be applied by brushing or spraying with the composition maintained at a temperature above its melting point (above 119 C. and usually ISO- C. for the sulphur mixes). The coating should usually be of the order of 50 to 100 mils thick and it will generally harden in from 30 seconds to 5 minutes although preferably the composition is alllowed to set for a somewhat longer time, e.g. 10 to 15 minutes if the structure is to be moved. The actual hardening time in any specific situation will depend on the plasticizer content, the hardening time increasing as the plasticizer content increases.

The invention is illustrated but not limited by the following example:

Concrete blocks (of the conventional 8" x 8" x 16" variety, weighing 36 pounds apiece) were stacked to form a Wall approximately 8' high and 10 long with a window in the center. The blocks were simply stacked one upon the other with no mortar or any other material between them leaving an appropriate opening for the window. When the wall reached a height corresponding to the top of the window, three blocks were butt-ended together on the ground and a molten glass fiber/ sulphur formulation at about 175 C. and with the composition described below was brushed over the vertical joints. The coating hardened within 30 seconds and the thus formed beam was then placed over the window opening as a lintel. Additional blocks were then stacked until the wall was completed. The glass fiber/sulphur formulation was then painted over the entire outside front and back of the wall. The coating was about inch thick, hardening in about 30 seconds, to give a wall which was not only superior in strength to a wall put up with mortar but also waterproof and decorative. The wall was stacked up and aligned in about 30 minutes using unskilled labor. Coating of the front and back surfaces of the wall using a spraying machine also took about 30 minutes. Hence, it will be appreciated that the process described herein offers a remarkably increased construction speed over conventional techniques with resultant saving of material and labor.

To demonstrate the superiority of the present construction method over conventional mortaring techniques, the following tests were conducted on the above wall:

A chain was passed from a boom-truck through the window in the wall. The wall was then lifted completely off the ground by means of the chain. This was readily accomplished without any undesired effects on the wall. The wall was then placed in a racking position, and there was again no failure in the wall. Finally, the wall was pushed over and allowed to fall flat on the ground with no significant damage to the joints in the wall.,

The glass fiber/ sulphur mix used in the above example comprised, on a parts by weight basis, 3 parts of chopped strand glass fibers (0.50 inch average length), 90 parts sulphur, 0.5 part coloring matter and 6.5 parts polysulphide plasticizer (mixture of equal parts of ZM399 and LP3). The composition was prepared by heating the mixtures to a temperature, between about l35-175 C. and stirring until the sulphur was melted and a uniform mix obtained.

As will be apparent from the foregoing, the present process can be used to give a wall which is finished, including decoration and waterproofing by simply stacking and painting. The resulting wall is much stronger, both in compression and tension, than walls made with corresponding blocks or building units using mortar or the like between the block's. Additionally, walls can be erected and finished in something of the order of onethird to one-half the time required for regular construction. Furthermore, the present invention simplifies certain construction problems, e.g., lintels above wall openings such as doors and Windows can be very easily made by joining several blocks together in a row and placing the resulting beam across the opening as described above. A particular advantage of the present invention is that the glass fiber/sulhpur formulations give a quick Waterproofing eifeot whereas, with conventional concrete block structures, it is necessary to wait for the mortar to dry before waterproofing can be effected. A further advantage of the present process is that it facilitates the use of concrete blocks or the like in climates where mortar cannot be conveniently used because of severe temperature conditions.

In a further embodiment of the invention, it has been found that polyester fiber (e.g., Dacron polyester) may be used as the fibrous component of the present compositions in admixture with sulphur and/or plastics as hereinabove described. Such polyester fibers are more flexible than glass fibers and in certain situations are preferable. Any synthetic polyester fiber or other fibrous material such as nylon, orlon and rayon which has high tensile strength (e.g. 50,000 pounds per square inch or higher) is useful for resent purposes provided the tensile strength and fiber integrity are maintained at temperatures used, e.g., temperatures between the melting point of sulphur 119 C. up to 175180 C. or even higher. Other suitable fibers for use with sulphur or other plastic material include natural fibers such as istle, manila hemp, sisal, abaca and jute. These natural fibers demonstrate tensile strengths in the range of about 74,000 to 150,000 feet and retain their fiber integrity at the desired formulaing and applicating temperature. (This tensile strength is reported on the basis of breaking lengthsthe product of the breaking strength and the number of feet to the pound of yarn tested; see Kirkothmers Encyclopedia of Chemical Technology, vol. 6, p. 468.) Asbestos fibers are not suitable due to their lack of flexibility and other undesirable characteristics. Cotton and wool fibers are likewise unsuitable because of their low tensile strength.

The amount of glass fibers or other fibrous material utilized can be widely varied and will depend on other operating factors such as the nature of the fibrous material. Usually, however, the amount of fibers used will fall in the range of from 1 to 50% by weight of the overall composition. In the case of chopped strand glass fibers, highly effective results are obtainable using lower loadings, e.g., from 1 to 15% by weight of the total composition whereas single strands or filaments of glass may require the use of 40-50% by weight to obtain equivalent results. With polyester fibers, excellent results are obtainable with as little as 1% polyester, based on the overall compositions, but substantially more than this amount of polyester may also be used if desired.

While in general the coating composition of the invention is applied to both surfaces of, for example, a vertical wall, it is essential that the composition be applied at least to that side of the wall or other structure which is to be subjected to tensile stress. Thus, in the case of a vertical wall with an internal surface and an external surface, the composition should be coated at least on the internal wall surface if the anticipated tensile stress will be applied to the external surface and in a direction normal thereto. Since it is generally difl"1- cult to predict the direction of stress, it will usually be preferable to apply the coating to both sides of the wall to cover all possibilities. This emphasizes an important characteristic of the coating composition used herein, namely, the high tensile strength thereof.

Although the invention is applicable to a wide variety of structural materials, as noted above to give various types of building structures, the materials utilized should be characterized by substantial compressive strength as represented by the usual types of wood and concrete structural materials,

It will be appreciated that other modifications may be made without deviating from the invention as defined in the following claims, wherein I claim:

1. The method of erecting a structure with building units which comprises stacking the units to form the desired structure without the use of any bonding medium on the contactingsurfaces of the stacked units and then coating at least one of the exposed external surfaces of the resulting structure at least about the periphery of said units by applying thereto a composition consisting essentially of glass fibers uniformly dispersed in molten and plasticized sulphur and allowing said molten sulphur composition to solidify, said coating serving as the sole essential means for bonding the units together, said sulphur being present in said composition in an amount at least 50% by weight of said composition, said sulphur being plasticized with a polysulphide plasticizer present in an amount from about 1% to about 30% by Weight of said composition and said glass fiber having a length of about 0.250.5 inch and present in an amount at least 1% by weight of said composition.

2. The method of claim 1 wherein said composition consists essentially of 5095 parts sulphur, from 1-30 parts plasticizer therefor selected from the group consisting of aryl polysulphides and aliphatic polysulphides wherein the bridging link between adjacent sulphur atoms includes aliphatic ether groups and from 1 to 50 parts glass fibers.

3. The method of claim 1 wherein said composition composition comprises 3 parts glass fibers having an average length of about 0.5 inch, parts sulphur and 6.5 parts polysulphide plasticizer.

4. The method of claim 1 wherein said composition includes an alkaline substance which is stable and does not discolor the coating composition.

5. The method of claim 4 wherein said substance is calcium carbonate.

6. The method of claim 1 wherein said structure is a vertical wall and the composition is applied toboth of the vertical surfaces of the wall.

References Cited by the Examiner UNITED STATES PATENTS 1,847,192 3/1932 Neuhaus 50536 2,835,126 5/1958 Palolella 50378 3,145,502 8/1964 Rubenstein 50-2'68 FOREIGN PATENTS 581 2/1950 Japan. 1,588 3/1954 Japan.

MORRIS LIEBMAN, Primary Examiner. A. LIEBERMAN, Assistant Examiner. 

1. THE METHOD OF ERECTING A STRUCTURE WITH BUILDING UNITS WHICH COMPRISES STACKING THE UNITS TO FORM THE DESIRED STRUCTURE WITHOUT THE USE OF ANY BONDING MEDIUM ON THE CONTACTING SURFACES OF THE STACKED UNITS AND THEN COATING AT LEAST ONE OF THE EXPOSED EXTERNAL SURFACES OF THE RESULTING STRUCTURE AT LEAST ABOUT THE PERIPHERY OF SAID UNITS BY APPLYING THERETO A COMPOSITION CONSISTING ESSENTIALLY OF GLASS FIBERS UNIFORMLY DISPERSED IN MOLTEN AND PLASTICIZED SULPHUR AND ALLOWING SAID MOLTEN SULPHUR COMPOSITION TO SOLIDIFY, SAID COATING SERVING AS THE SOLE ESSENTIAL MEANS FOR BONDING THE UNITS TOGETHER, SAID SULPHUR BEING PRESENT IN SAID COMPOSITION IN AN AMOUNT AT LEAST 50% BY WEIGHT OF SAID COMPOSITION, SAID SULPHUR BEING PLASTICIZED WITH A POLYSULPHIDE PLASTICIZER PRESENT IN AN AMOUNT FROM ABOUT 1% TO ABOUT 30% BY WEIGHT OF SAID COMPOSITION AND SAID GLASS FIBER HAVING A LENGTH OF ABOUT 0.25-0.5 INCH AND PRESENT IN AN AMOUNT AT LEAST 1% BY WEIGHT OF SAID COMPOSITION. 